Tension wood on poplar is formed at the upper face of branches and on bended stems in response to a gravitational stimulus. This tissue is characterized by: 1) the formation of gelatinous fibre cells, called G-fibres, containing high amount of cellulose; 2) the modification of lignin content and composition and 3) many changes in cell ultrastructure and wood physical properties. Althougth tension wood plays an important role in the tree architecture, the presence of a high proportion of this tissue is a major problem for several industrial applications. Using this experimental model, we intend to identify genes specifically regulated during tension wood formation in poplar, genes which may be involved in cellulose/hemicellulose synthesis, lignin metabolism or xylem differentiation. Towards this end, we used an Amplified Fragment Length Polymorphism-based technique for RNA fingerprinting referred as cDNA-AFLP to identify genes differentially accumulated in tension wood zone compared to opposite or upright wood. Poly (A)+ RNA were purified from total RNA extracted from xylem tissues harvested on poplar stems which have been bended for 2 months. Using this technique, we identified more than 100 transcript-derived fragments (TDFs) on cDNA-AFLP gels. On a total of 96 couples of primers tested we found more than 100 TDFs showing a differential amplification. Approximately 80% of the differentially amplified TDFs were shown to be specifically or mainly amplified from tension wood compared to opposite or normal wood samples. At that time, 40 of these TDFs have been cloned. Expression studies (RT-PCR, Reverse Northern) are currently carried on to confirm these sequences as differentially accumulated between tension wood, opposite wood or upright wood.